1. Field of the Invention
The present invention relates to a rotary electric machine such as an alternator, etc., and particularly to an output terminal construction used to direct output power from the rotary electric machine to external equipment.
2. Description of the Related Art
In conventional automotive alternators, an external screw thread portion is disposed at an opposite end of an output terminal bolt from an extraction end, the external screw thread portion of the output terminal bolt being securely fastened to a one-sided tightening nut secured by crimping to a penetrating aperture disposed on a positive-side cooling fin of a rectifier apparatus. At the extraction end of the output terminal bolt, a wiring harness terminal is securely fastened with a nut by means of an electrically-insulating bush made of a resin, a rear-end end frame, and another electrically-insulating bush made of a resin. (See Patent Literature 1, for example.)
Patent Literature 1: Japanese Patent Laid-Open No. HEI 9-107654 (Gazette, Paragraph [0009] and FIG. 2)
In conventional automotive alternators, a terminal that is electrically connected to an automotive vehicle wiring harness is inserted into the output terminal bolt and securely fastened with a nut to output electric power to automotive vehicle equipment. Now, in an electrical conduction pathway leading from the positive-side cooling fin to the output terminal bolt, a coupling portion between the external screw thread portion at an opposite end of the output terminal bolt from an output extraction end and the one-sided tightening nut interposes, and in an electrical conduction pathway leading from the output terminal bolt to the wiring harness terminal, a coupling portion between the external screw thread portion at the output extraction end of the output terminal bolt and the nut interposes. Electrical resistance at these coupling portions is large, increasing the heat generated at the coupling portions during the extraction of high-output electric current.
Thus, heat generated at the coupling portion at the opposite end of the output terminal bolt from the output extraction end gives rise to temperature increases in diodes constituting a rectifier apparatus that are disposed in close proximity to the output terminal bolt. Heat generated at the coupling portions at the output extraction end of the output terminal bolt also gives rise to heat degradation and thermal contraction of electrically-insulating bushes made of a resin, loosening the coupling by the nut, thereby giving rise to reductions in the force fastening the wiring harness terminal to the output terminal bolt.